Previously, many types of retainers have been used in endeavoring to provide an effective means for retaining a patient's teeth after orthodontic corrections of malocclusions have been made. Most of the prior art utilizes the same basic approach as the orthodontic appliance used to make the original rectification, as in most cases, the appliance is rigid and designed to place pressure at specific points and areas. The prior retainers utilized a combination of steel wire, springs and elastic bands, along with a thermoset plastic bridge most commonly using a hard acrylic, such as methyl methacrylate.
The Hawley retainer is well known in the art and has been in use for many years. This retainer consists of acrylic covering the full palate, along with the lingual mucosa area and is sometimes vented to expose selected palatal regions. While prior art has accomplished much using rigid materials, a search did not disclose any patents that rely upon resilient structure for retention, however, the following U.S. patents are considered related.
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 5,376,001 Tepper Dec. 27, 1994 5,167,499 Arndt et al Dec. 1, 1992 5,096,416 Hulsink Mar. 17, 1992 4,976,614 Tepper Dec. 11, 1990 4,468,196 Keller Aug. 28, 1984 4,433,956 Witzig Feb. 28, 1984 4,416,626 Bellavia Nov. 22, 1983 4,028,808 Schwartz Jun. 14, 1977 3,162,948 Gerber Dec. 29, 1964 1,582,570 Brust Apr. 27, 1926 ______________________________________
U.S. Pat. No. 5,376,001, issued to the present inventor, discloses a removable orthodontic appliance which utilizes a similar pair of clasps seated over midregion teeth connected to a labial arch wire. A pair of structural braces, either molded wings or connecting sections are attached to a radial loop of metal forming a palatial bridge. The loop preferably made of memory metal having the consistent tendency to return to its original state exerts persistent linear force in the opposite direction of deformation. The clasp is made of three pieces of tube and wire, and wings that are formed of rigid mono-methylate, which sets quickly under ultra violet light.
Arndt et al, in U.S. Pat. No. 5,167,499, disclose a removable orthodontic palatial expansion arch in an "M" shape of nickel titanium wire attached to a metal band surrounding the upper first permanent molars.
U.S. Pat. No. 5,096,416 of Hulsink teaches an orthodontic retainer made of hard non-moving acrylic sections interconnected by resilient wires. A spring arm made of acrylic covered wire engage the labial surfaces of the four front teeth. A pair of Adam's clasps supported by a rigid plate extend over the first molar assisting in clasping the retainer in place. It will be noted that all of the plates are rigid and the resiliency is provided by flexible wires.
U.S. Pat. No. 4,976,614, also issued to the present inventor, utilizes midregion clasps and a label filament serving as a reference arch, along with a curved lingual spring filament urging the teeth against the reference. Synthetic resin filaments of transparent material hold the teeth to prevent relapse. A sinuous palatal arch wire, continuous in form, but having cyclic variations, extends across the patient's palate and provides a spreading force upon clasps attached to opposed pre-molar or bicuspid teeth. In another embodiment opposed facing palatal wings of hard material encompass the gingival region of a number of molars and include a wire arch device which extends back across the roof of the patient's mouth.
Keller's U.S. Pat. No. 4,468,196 employs a method of treatment and an apparatus which includes bands around selected molars and an arch wire with springs that exert a specific force. A bracing wire is placed in contact with the buccal surfaces of the front teeth and is covered with a hardenable acrylic.
Witzig, in U.S. Pat. No. 4,433,956, employs acrylic anterior segments over the front teeth in conjunction with an expandable screw, connecting a similar posterior segment over the mid-range teeth. The appliance is adjusted in stages to correct lower jaw movements.
U.S. Pat. No. 4,416,626, issued to Bellavia, teaches a method and apparatus which utilizes acrylic wings with caps that cover screw adjusting mechanisms and alignment pins.
For background purposes and as indicative of the art to which the invention is related, reference may be made to the patents issued to Schwartz, Gerber and Brust.